I recently started my diploma thesis in physics and am supposed to model aerosol dispersion, but I'm totally new to the topic of CFD, so if anybody could help me with some basic questions I'd really appreciate it.

My situation is the following:

I inject dust (particle size between 2 and 25 micrometer) into air and measure how far the cloud disperses due to turbulent diffusion. After measuring the vertical distribution of my cloud using a PIV system, I want to compare this to my model, but that's where I got stuck.

A friend suggested to use OpenFoam, so my first question is if it's in general possible to model this scenario? Anyone every done this before? And how do I best get started?

Yes, it would definitely be possible to solve that type of problem. There are different kinds of flow solvers, however if you are not interested in the transient problem, then I would suggest that you choose simpleFOAM with an appropriate turbulence closure model. If the transient part is important, then I would suggest turbFoam.
With respect to the advection-diffusion problem of the particles, then I suppose that a bulk-approach will be the only feasible way to look into the problem, i.e. solve an equation describing the spatial and temporal variation in the concentrations. Here the only significant deviation from a standard advection-diffusion problem will be the inclusion of a certain fall velocity of the particles.
If you have several particles, then you could either make a set of equations each solver for c1 (d < 1mikron), c2 ( 1 mikron < d < 3 mikron), etc. or simply define a representation fall velocity.

Yes, it would definitely be possible to solve that type of problem. There are different kinds of flow solvers, however if you are not interested in the transient problem, then I would suggest that you choose simpleFOAM with an appropriate turbulence closure model. If the transient part is important, then I would suggest turbFoam.
With respect to the advection-diffusion problem of the particles, then I suppose that a bulk-approach will be the only feasible way to look into the problem, i.e. solve an equation describing the spatial and temporal variation in the concentrations. Here the only significant deviation from a standard advection-diffusion problem will be the inclusion of a certain fall velocity of the particles.
If you have several particles, then you could either make a set of equations each solver for c1 (d < 1mikron), c2 ( 1 mikron < d < 3 mikron), etc. or simply define a representation fall velocity.

myself i am working on the indoor air purifier, where the room consists of 90% air and 10% dust, since i want to see how the particles are moving considering the purifier removes the dust completely with time. please suggest me the solver on which i can work